Jet ignition system



Jan. 16, 1962 R. F. GAMBLE ET AL JET IGNITION SYSTEM 2 Sheets-Sheet 1 Filed Sept. 9, 1960 INVENTORS RICHARD E GAMBLE ROBERT s. LANCTOT BY W WW A 7'TORNEV Jan. 16, 1962 R. F. GAMBLE ET AL JET IGNITION SYSTEM 2 Sheets-Sheet 2 Filed Sept. 9, 1960 INVE NTURS RICHARD E GAMBLE ROBERT S. LANGTOT 14 file/M ATTORNEY termined value.

Unite States Patent fiice 3,016,706 Patented Jan. 16, 1962 3,016,706 JET IGNITION SYSTEM Richard F. Gamble, Simsbury, Conn., and Robert S. Lanctot, Longmeadow, Mass, assignors to United Aircraft Corporation, East Hartford, Comm, a corporation of Delaware Filed Sept. 9, 1960, Ser. No. 54,908 16 Claims. (Cl. 6039.82)

This invention relates to an ignition system for an internal combustion type of engine and more specifically to means for initiating combustion in a combustion charnber of an engine by utilizing a pyrophoric fuel compositio-n.

Since the advent of high altitude aircraft and outer space vehicle, the need for an ignition system that would afford satisfactory reliability characteristics has become increasingly prevalent. Of course, such an ignition system must afford not only a high degree of reliability, but also must have the other economical and engineering characteristics that are a necessary requirement for any device designed for aircraft use. The development and use of pyrophoric chemicals has in the past few years shown qualities whichmake their use in an ignition system a feasible reality. Up to present, the industry has seen several attempts in chemical ignition systems which inject a spontaneous flammable chemical in the combustion chamber for initiating combustion, but these systems have been directed to afterburners and rocket devices. In afterburners, for example, the ambient air within the passage of the afterburner is at an extremely high temperature, so that it has been possible to initiate combustion with certain chemicals that decompose in the presence of a catalyst. And in rockets, for example, an immiscible igniting chemical has been combined with the bulk or noruponactuation of the normal fuel controls. 7 These igniting methods, however, do not lend themselves to igniting a main burner, for example in a turbine type engine, since in some cases the ambient condition within these engines would not lend itself for combustion or in other cases the initiation of combustion would not be repetitive. Of course a desirable feature for any chemical ignition system would be to have ignition take place in flight as well as initial starting, as might be expected if a failure should occur during normal flight.

We have devised an ignition system which weighs less thanthe usual electrical system and which has exhibited superior reliability characteristics, in' which, incidentally, test results conducted to date have been so successful that there has not been a single failure in starting. The system that we have devised is automatic wherein firing or refiring of the system will occur should the pressure of the normal fuel injected into the engine decrease to a prede- The events of operation for firing and refiring are: (l) Arming the ignition system in preparation for firing upon evidencing a decrease in main fuel pressure, and (2) subsequently injecting the ignition fuel when the main fuel pressure in the manifold reaches a predetermined value. This ignition system also lends itself to be readily adaptable to all types of internal combustion engines, such as jet, turbo-jet, rocket, ramjets, etc. Further this novel device which we have invented can be similarly utilized to initiate combustion in an afterburner device, as Well as arranging two identical systems in a novel manner for initiating combustion in both the main burner and afterburner.

Itis an object of this invention to provide a system for igniting an internal combustion engine by a chemical composition whichis characterized as being spontaneously flammable when in the presence of another chemical element.

mal fuel so that initiation of combustion would occur It still is a further object of this invention to provide an ignition system of the type described for automatically injecting a predetermined finite charge of an ignition fuel into the engine wherein actuation takes place when the main or normal fuel pressure has reached a predetermined value.

It is still a further object of this invention to provide an automatic ignition device which is capable of repetitive firing.

And still a further object is to provide a system which is characterized by being light in weight, readily adaptable for existing engines and highly reliable.

It still is a further object of this invention to provide an igniter system as described which lends itself to be readily adaptable to accommodate an identical system for igniting the afterbur ner.

Other objects and advantages will be apparent from the specification and claims, and from the accompanying drawings which illustrate an embodiment of the invention.

FIG. 1 is a block diagram illustrating two parallel ignition systems connected to initiate combustion in a main burner and after-burner.

FIG. 2 is a schematic illustration of a. preferred embodiment of this invention.

Referring particularly to FIG. 1 which shows a preferred system adapted to initiate combustion in a' main burner and afterburner wherein numeral 10 generally indicates a turbine type power plant having a main combustion section 112, fuel nozzles (not shown) which are normally supplied with fuel through fuel manifold 15. The aft end of the engine may carry a well-known type of afterburner which serves to augment the thrust of a jet type of engine and is generally indicated by numeral 14, having its separate main fuel nozzles 16 connected to main fuel manifold 18. Conduits 20 and 22 connect the chemical ignition systems generally indicated by numerals 24 and 25 to the ignition nozzles 26 and 28 respectively. As will be more fully described hereinbelow, the igniter fuel is injected into the engine for initiating combustion through these connections. It is to be understood that the exact location of the igniter nozzles is shown here merely for illustrative purposes, but may be located anywhere so long as it is in the proximity of the fuel issuing from the main fuel nozzles. In the usual turbine type engine, the main fuel may he directed to the main burner manifold from. tank 30 via pump 32 through the fuel control 34 and into the main fuel manifold 36. The

fuel control serves to regulate the quantity of fuel to the engine and may be of any suitable type. An example of a suitable fuelcontrol is shown in Stanley G. Bests Patent No. 2,822,666, granted on February 11, 1958. As will be realized, igniter fuel tank 33 supplies igniter fuel to both the main burner igniter 24 and afterburner igniter 25. Both the igniter devices are identical in structure and function, and for simplicity, only one of the systems will be described. In its preferred form, however, the supply line for loading the pump with a finite charge of igniter fuel would be connected directly to the pump inlet valve of the afterburner igniter and in flow series with the pump inlet control of the main burner igniter.

FIG. 2 shows the ignition system 24 for the main burner, which comprises igniter fuel tank 3-8, metering pump 40, pump inlet control valve 42, pump outlet control valve 44, and actuator 46. Tank 38 is preloaded with the chemical ignition fuel, for example, the triethylaluminumor triethylborane compounds. The tank is pressurized with a suitable gas such as nitrogen and sealed. For safety reasons, an emergency dump valve 51 which may be manually and/or automatically operated may be disposed in line 52 to quickly dump fuel out of the system and overboard.

The ignition fuel is fed into the pumping chamber 50 of metering pump 40 by supply line 52 and conduit 54, where in turn it flows through valve passage 55 into annular chamber 57 and then to line 58. When in the off or armed position as shown, the pump piston 56 is re tracted to its upward position so that it will create a volume which will hold a finite charge of igniter fuel which is to be used for initiating combustion. Valve 42 is disposed between conduits 58 and 54 and serves to open and close the connection between the pumping chamber 50 and the tank 38, as will be more fully described hereinbelow. The left-hand end of spool 60 of valve 42 a'buts against the right-hand end of the valve 62 whereby the valve 60 is normally held Open while valve 62 is normally held closed by the force created by return spring 64. When a firing is desired for igniting the engine during starting, for example, the main fuel will first be injected into the burner section through the fuel manifold, and when this fuel pressure in the manifold reaches a predetermined value, which at the same instant is substantially the same pressure sensed in cylinder 70, acting on the underside of piston 72 of actuator 46, this pressure will thus cause piston 72 to move toward the right against the force generated by spring 74, which movement further causes the piston rod 76 to position linkage member 78 to the right for simultaneously unseating and seating valve 62 and valve 60 respectively. Of course, this prevents communication between the tank 38 and the pumping chamber- 58 and simultaneously puts '56 is subjected to the pressure in chamber "57, which will be essentially the same as the pressure in tank 38. Branch conduit 80 connects chamber 57 to tank '38 so that the fluid pressure in chamber 57 is substantially equal to the pressure of the fluid in the tank, and since the pressure in chamber 57 is at a higher value than thepressure in the burner chamber, piston 56 will be driven downwardly for delivering a finitecharge of igniter fuel to the combustion chamber via lines 58 and 20. When the normal fuel and igniter fuel combine in the burner chamber, spontaneous combustion will result, thus initi- 'ating combustion.

Still referring to FIG. 2, it will'be seen that piston 56 carries .a centrally disposed depending .arm 82 which, when "at its downward stroke, engages'the right-hand end of disengaging lever 84. This causes lever .84 to pivot 'around pin 86 which in turn rotates shaft '88. Arm 190 is secured to the shaft and rotates therewith and engages depending arm 92 of connecting link 94. When the piston is at its downward stroke, this mechanism just described causes connecting link 94 to rotate clockwise about-the pin connection 94 so that the left bottom surface rides on top of roller 100 which vis secured t linkage member 78. The force created by.spring 64 thus "forces the valving mechanism 42 and 44 to unseat and seat respectively. As long as the .fuel pressure in the fuel manifold remains above the predetermined actuating pressure required to position piston 72, the valving mechanism, i.e. linkage member 78 will be disengaged from actuator 46. Bellows 89 serves to seal the actuating mechanism from the fuel contaminated mechanism.

Fromthe foregoing, it is apparent that since valve 42 is in its open position, pumping chamber 50 will be recharged with igniter'fuel and ready for refiring. Should combustion cease for any reason in the engine, a lowering in the fuel pressure in the manifold will normally be evidenced on the underside of piston 72, which will, under the force of spring 74, permit pistion 72 of actuator 46'to return to its left or standby position. Thisin turn permits connecting link 94 to return to its left position by return spring 104 and spring 166 reset the connecting link back on its line-on-line position. Therefore, it will be realized that the ignition device will be in its refiring position and subject to initiating combustion 7 when the pressure in the fuel manifold has again reached its predetermined value, and ignition will occur in the same manner as has been described above.

In order to prevent the ignition system from initiating ignition inadvertently, compressor discharge pressure (which pressure is substantially equal to burner pressure) is admitted into cylinder 79 to act on the upper reaction surface of piston 78. In this manner the actuating piston 78 is subjected to the pressure differential across the fuel injecting nozzle (not shown). Of course, in an afterburner application, a pressure that would indicate the pressure differential across the afterburner fuel nozzle would also be preferentially sensed across the actuating piston, Thus, for example, should the compressor of a turbine type of power plant be rotating while the fuel is being blocked off, the pressure in the fuel manifold would be substantially equal to compressor discharge pressure, and if the pressure behind piston 72 were at a lower value, say outside ambient pressure, then the ignition fuel system would inadvertently be actuated.

What has been shown by this invention is an extremely reliable ignition system that serves to repetitively initiate combustion in an internal combustion engine. The igniter is characterized as being readily adaptable for all types of combustion engines and particularly those intended for flight vehicles.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described but may be used in other ways without departure from its spirit as defined by the following claims.

We claim:

1. In a chemical ignition system for an internal combustion engine'having compressor and a combustion section, a first source of fuel under pressure, means for regulating the flow of fuel from said source to said combustion sectionya sourceof ignition fuel, means for injecting into said combustion section a finite charge of said ignition fuel, means responsive to a pressure of the main fuel for producing a first signal, said means also responsive to the pressure of air discharging from said compressor for producing a second signal, means responsive to said signals to actuate said injecting means at a pre determined value of said signals. 7

2. In an ignition system for igniting fuel in an internal combustion engine having a burner section, a normalfuel system communicating with said burner. section, the ignition system having a separate communicating means with said combustion section, a source of igniter fuel, automatic means for injecting a finite charge of said igniter fuel through said communicatingjmeans into said burner section, said last means comprising a pump being motivated by said igniter fuel, actuator means being responsive to a condition of the normal fuel for actuating said pump.

3. In an'ignition system for igniting fuel in an internalcombustion engine, a duct having its free end'in the engine and communicating with said ignition system,

'said system having a pump, a source of igniter fuel under pressure, said pump for delivering to the engine a finite charge of the igniter fuel through said duct, first and second valve means associated with said duct for simultaneously'placing the pump in communication with said engine and blocking off the supply of igniter fuel from said pump, said valve means responsive to a condition of the igniter fuel so that the main fuel will be admitted'to the engine prior to the admittance of the igniter fuel.

4. In an ignition system for an internal combustion engine having a combustion section, a source of main fuel underrpressure, means for delivering said fuel to the combustion section, a source of igniter fuel, a pump having a fluid chamber adapted to receive a predetermined quantity of igniter fuel, means defining a passage connecting the fluid chamber to the combustion section, at least one valve disposed in said passage functioning to normally block the flow of igniter fuel in the passage, means responsive to a condition of the main fuel for producing a signal, means for converting said signal into opening movement of said valve so that the igniter fuel is injected into the engine in the vicinity of and subsequent to the main fuel whereby spontaneous igniting of said igniter fuel will occur for inducing co-mbus tion of the main fuel.

5. In a chemical ignition system for an internal combustion engine having a burner chamber, a source of main fuel, a fuel control regulating the flow of fuel from said source to said burner chamber, a separate source of ignition fuel, means for injecting said ignition fuel into the burner chamber at a point which is in the proximity to where the main fuel is being injected, said means comprising an actuator having a moveable member and an arm extending axially from and attached to said member, a pair of valves operatively connected to said arm, a pump, fiuid passage means connecting said separate source to said pump and said pump to said burner chamber wherein one of said valves is disposed in said passage means and communicates said pump with said separate source and the other of said valves is also disposed in said passage means and blocks off communication from said pump to said burner chamber, means responsive to a condition of said main fuel and means for receiving said responsive means for controlling the position of said moveable means so as to reverse the operation of said valves.

6. A chemical ignition system for an internal combustion engine comprising a source of ignition fuel under pressure, a pump, first and second valve means, said first valve normally directing fluid to said pump, said second valve normally blocking off flow from said pump to said engine, an actuator responsive to a condition of said engine and operatively connected to said valves and including a linkage member normally held in ine-on-line position with one of said valves, said first and second valves being positioned so that said first valve blocks off fuel from said source to said pump and said second valve directs fluid from said pump to said engine, means responsive to the position of said pump for disturbing the line-on-line position of said linkage, means attached to said linkage for returning the linkage to the line-on-line position upon the actuator reaching a predetermined position in accordance with said engine condition.

7. A chemical ignition system for an internal combustion engine comprising a source of igniter fuel under pressure, a pump, a first conduit connecting the pump to said source, a second conduit connecting the pump to the engine, first and second valve means one of each cooperating with one of each of said conduits for directing fuel into and out of said pump, an actuator having a moveable piston member and a casing enclosing said piston, said casing and said piston defining a pair of fluid expansion chambers, an elongated rod secured to the piston and moveable therewith, said rod operatively connected to said valves for urging said valves in one direction, spring means attached to at least one of said valves for urging both valves in an opposite direction, said valves being urged in one of said directions upon the pressure of the fluid in said expansion chambers reaching a predetermined value.

8. A chemical ignition system for an internal combustion engine having a fuel control system including a main fuel feed nozzle, said system comprising a separate source of igniter fuel, means responsive to the pressure differential across said nozzle for producing a signal, an actuator for receiving said signal and having a moveable member, a pump having a pumping chamber for holding a finite charge of igniter fuel, first valve means for directing igniter fuel into said chamber, second valve means for directing said finite charge to said engine, said valve means synchronously operable so as to allow the one valve means to remain in its opened position while the other valve means remains in its closed position, said moveable member cooperating with said valves for synchronously reversing the position of each of said valves upon reaching a predetermined value of said pressure differential.

9. A chemical ignition system for an internal combustion engine having a fuel control system including a fuel feed nozzle, said system comprising a source of igniter fuel under pressure, an actuator device having a cylinder, an axially moveable piston disposed in the cylinder and forming a pair of opposed fluid expansion chambers, one of said chambers being responsive to the pressure of the main fuel and the other chamber being responsive to an engine operating pressure, a pump fluidly connected to said igniter fuel source capable of discharging a finite charge of igniter fuel to said engine, said igniter fuel also functioning to drive said pump, valve means operatively connected to said piston and adapted to simultaneously direct the flow of igniter fuel from said source to said pump and from said pump to said engine in accordance with the fluid pressures in said chambers.

10. In combination with an ignition system having a standby and a firing position, an internal combustion engine having a main fuel control system including a fuel conducting passage, said ignition system comprising a source of igniter fuel, a pump, an actuator responsive to the pressure of fuel in the passage, valve means operatively connected to said actuator and directing the fiow of igniter fuel from said source to said pump and alternately directing the flow of igniter fuel from said pump to said engine, said actuator placing the igniter system in a standby position in response to a low fuel pressure sensed in said passage and also placing said ignition system in a firing position in response to a high fuel pressure sensed in said passage.

11. In a chemical ignition system for a combustion engine having a main combustion chamber and an afterburner combustion chamber, a source of main fuel under pressure, means for regulating the flow of main fuel from said source to both of said combustion chambers, a source of igniter fuel under pressure, means including a single pump for injecting into each of said combustion chambers a finite charge of said ignition fuel, means responsive to the pressure of the main fuel for producing a signal, and means responsive to said signal for actuating said injecting means.

12. In a chemical ignition system for a combustion eng-ine having a main combustion chamber and an afterburner combustion engine having a main combustion chamber and an afterburner combustion chamber each including separate fuel feed nozzles, a source of main fuel under pressure, means for regulating the flow of main fuel to both of said combustion chambers, said ignition system comprising a single pump having a pumping chamber, a source of ignition fuel under pressure, means for directing the flow of igniter fuel to and from said pumping chamber including valve means, means for sensing the main fuel pressure upstream of said nozzles for varying the position of said valves, said means comprising a pair of movable members including elongated arms mounted thereon and operatively connected to said valves, each of said actuators being mounted in parallel relation to each other, and each actuator adapted to induce ignition independently of the other.

13. In combination with an internal combustion engine having a main burner section and an afterburner section, a fuel supply system including means for regulating the flow of main fuel to said main burner section and said afterburner section and including a fuel feed nozzle associated with each of said burner sections, an ignition system adapted to initiate combustion in each of said sections and having a standby position and a firing position, a pair of actuators each including means responsive to the pressure differential across each of said nozzles, a source of igniter fuel under pressure, a pump, a first valve switching means for directing igniter fuel from said source to said pump and alternately to said main combustion section from said pump and a second valve switching means for directing igniter fuel from said source to said pump and alternately to said afterburner section from said pump, one of each of said actuators associated with one of each of said valve means and means for operatively connecting each of said switching means to said actuators so that said connecting means cause the ignition system to be placed in a standby position at a first predetermined value of said pressure differential across either of said nozzles and also said connecting means cause the ignition system to be placed in a firing position at a second predetermined value of said pressure diflerentital across either of said nozzles, the standby and firing positions for either the main burner section or the afterburner section operable independently of each other.

14. In a chemical ignition system having a source of fluid under pressure, an actuator, 21 valve including operative connections to said actuator, a pump for pumping a finite charge of fluid, said pump comprising a casing having a fluid connection serving as an inlet and outlet passage, said casing having a cavity portion for housing a piston, said piston movable in an axial direction and having a reaction surface for-med on one surface of said piston and forming an expansion chamber in said cavity, a spring acting on the opposite surface of said piston means for communicating said chamber with said fluid source, and means for actuating said pump whereby the pressure from said fluid source serves as the motivating force. for moving said piston in a direction opposing the force of said spring.

15. In a chemical ignition system having a pump, a source of fluid under pressure, means for actuating said pump, a linkage device associated with said actuating device for disengaging said actuating means, said pump comprising a casing having fluid inlet and outlet conducting means, a movable piston disposed in said casing and having a reaction surface forming a variable volume fluid chamber, a connection between said fluid source and said chamber, said fluid acting on said reaction surface for driving the piston upon actuation by said actuating means.

16. In a chemical ignition system for injecting a finite charge of fluid into an engine including a pump, said pump having a casing, a movable member disposed in said casing and; forming a pair of fluid accommodating chambers, passage means connecting said casing for admitting said fluid into either of said chambers, means for actuating said pump including an actuator, said fluid in one of said chambers serving as the force for driving the piston in one direction, spring means for urging said piston in an opposite direction, said actuator having an elongated movable member, a lever member operatively connected to the piston in at least one position of its stroke for placing said actuator in an inoperative condition.

References Cited in the file of this patent UNITED STATES PATENTS 

